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([2601:600:947f:f020:85dc:d2b2:c5ee:e3c4]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4e8aaf3370fsm74330521cf.3.2025.10.21.06.39.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Oct 2025 06:39:14 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: Date: Tue, 21 Oct 2025 09:39:10 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 13/33] cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset To: Frederic Weisbecker , LKML Cc: =?UTF-8?Q?Michal_Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org References: <20251013203146.10162-1-frederic@kernel.org> <20251013203146.10162-14-frederic@kernel.org> In-Reply-To: <20251013203146.10162-14-frederic@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: zz4A1ZqKu15bvcmrTLsKYeLZF28gvST8MdaBXK90O1E_1761053956 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4F1991C0007 X-Stat-Signature: obkoo1fj71rusxaf4kmesgn1uembkppt X-HE-Tag: 1761053958-916653 X-HE-Meta: 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 Hlt/zz/9 B4qpNeB/wMiPXtUodNmbAe8rUKmrq6q1N8PLJ0G4ojNMFoyzeAYSug3PIEaaCAmBgo9wqsF1ivd3txprZq+x2O/SZZmLUNCOdUslo+tLFDmHoR7Y954+s3PAxsyYmhnVDt6zhDLKWj2+5v/9lyxiQM1LzVx0QtT45XIOPG1T055UWMVxoDBFh6wsfnJSmYQeQ7yYmgD4AGo0mi3DSZLBFduRdKQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/13/25 4:31 PM, Frederic Weisbecker wrote: > @@ -80,12 +110,45 @@ EXPORT_SYMBOL_GPL(housekeeping_affine); > > bool housekeeping_test_cpu(int cpu, enum hk_type type) > { > - if (housekeeping.flags & BIT(type)) > + if (READ_ONCE(housekeeping.flags) & BIT(type)) > return cpumask_test_cpu(cpu, housekeeping_cpumask(type)); > return true; > } > EXPORT_SYMBOL_GPL(housekeeping_test_cpu); > > +int housekeeping_update(struct cpumask *mask, enum hk_type type) > +{ > + struct cpumask *trial, *old = NULL; > + > + if (type != HK_TYPE_DOMAIN) > + return -ENOTSUPP; > + > + trial = kmalloc(sizeof(*trial), GFP_KERNEL); Should you use cpumask_size() instead of sizeof(*trial) as the latter can be much bigger? > + if (!trial) > + return -ENOMEM; > + > + cpumask_andnot(trial, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT), mask); > + if (!cpumask_intersects(trial, cpu_online_mask)) { > + kfree(trial); > + return -EINVAL; > + } > + > + if (!housekeeping.flags) > + static_branch_enable(&housekeeping_overridden); > + > + if (!(housekeeping.flags & BIT(type))) > + old = housekeeping_cpumask_dereference(type); > + else > + WRITE_ONCE(housekeeping.flags, housekeeping.flags | BIT(type)); > + rcu_assign_pointer(housekeeping.cpumasks[type], trial); > + > + synchronize_rcu(); > + > + kfree(old); If "isolcpus" boot command line option is set, old can be a pointer to the boot time memblock area which isn't a pointer that can be handled by the slab allocator AFAIU. I don't know the exact consequence, but it may not be good. One possible solution I can think of is to make HK_TYPE_DOMAIN and HK_TYPE_DOMAIN_ROOT point to the same memblock pointer and don't pass the old HK_TYPE_DOMAIN pointer to kfree() if it matches HK_TYPE_DOMAIN_BOOT one. Alternatively, we can just set the HK_TYPE_DOMAIN_BOOT pointer at boot and make HK_TYPE_DOMAIN falls back to HK_TYPE_DOMAIN_BOOT if not set. Cheers, Longman